1. Field of the Invention
The present invention relates to a seal assembly in a concentric shaft assembly, and more specifically to a seal assembly in a concentric shaft assembly that prevents mixing of two fluids that leak past the seals.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98
In a turbo-pump, such as one used in a rocket engine, a fuel and an oxidizer are mixed in the combustion chamber to propel the rocket. Since the turbopump is subjected to both the fuel and the oxidizer, the turbopump requires an inter-propellant seal (IPS) to maintain separation between the fuel and the oxidizer to prevent premature combustion. Such a seal arrangement is disclosed in U.S. Pat. No. 6,976,679 B2 issued on Dec. 20, 2005 to Goss et al and entitled INTER-FLUID SEAL ASSEMBLY AND METHOD THEREFOR. In the Prior Art, a series of knife-edge, labyrinth, and contacting seals are spaced along with purge and drain cavities to capture any leakage of the fuel and the oxidizer, collect the leakages in separate cavities, and discharge the leakages from the turbopump without any mixing of the leakages.
In a turbopump that has dual spools that form concentric shafts, there would be a need to also seal the cavity between the two concentric shafts and prevent any leakages from mixing as described above. There is a need in the prior art to provide for a seal assembly between concentric shafts to prevent mixture of leakages of materials that would react, and to discharge the leakages from the apparatus without mixing the two fluids.